Seismic Swing Teacher Guide Seismic Swing
Teacher Facilitation Guide • Middle School STEM Club
45 MIN SESSION
Session Overview
Students will explore the physics of Harmonic Motion by constructing a DIY Seismograph. By suspending a "pendulum" marker over a moving paper strip, they will visualize how restoring forces create cyclical patterns.
Learning Objectives
Define harmonic motion as repeated back-and-forth movement.
Identify the restoring force in a pendulum system.
Measure amplitude (distance from center) and calculate frequency (cycles per second).
Materials Needed
Cardboard boxes (Medium)
Paper cups (12oz)
String / Twine
Felt-tip markers (Heavy)
Rolls of paper strips (or 2" cut)
Tape & Scissors
Weights (Pennies or washers)
Instructional Sequence
05
Warm-up: The Harmonic Challenge
Show the multiple-choice segment of the video (Starting at 7:22).
"Divide the club into teams. Use a buzzer or hand-raise. For each scenario (Chandelier, Ocean Swell, etc.), teams must yell 'HARMONIC' or 'NOT HARMONIC' and explain why (is there a restoring force?)."
30
Main Activity: DIY Seismograph Build
1. The Frame: Cut two slits in the bottom edges of the box for the paper strip to slide through.
2. The Pendulum: Poke holes in a cup and hang it from the top of the box with string. It should hang about 1 inch above the bottom.
3. The Pen: Poke a hole in the bottom of the cup and wedge the marker through. Add weights (washers) to the cup to keep it stable.
4. Calibration: The marker tip should just barely touch the paper strip as it slides underneath.
10
Analysis: Quake Data
Students pull the paper at a steady pace while a partner "shakes" the table.
Amplitude: Measure from the center line to the peak of the wave.Frequency: Count how many "peaks" appear in a 5-second pull. Divide by 5 for Hertz (Hz).
Club Leader Pro-Tips
Troubleshooting
If the marker is dragging too hard, the paper won't move. Adjust the string length so the marker tip "kisses" the paper. Using heavy markers or adding more weight to the cup helps!
Deep Dive
Relate the build back to the video's "Ocean Swell" example. Just like the water rises and falls, our marker rises and falls (relative to the paper) in a repeating cycle.
Seismic Swing Slides SEISMIC
SWING
The Physics of Harmonic Motion
STEM CLUB CHALLENGE
Warm-up Challenge
The Rulebook:
Watch the clip (starts at 7:22)
Buzz in for each scenario
Explain the "Restoring Force" to win
Embedded media
Lab Vocabulary
Restoring Force
The "invisible hand" that always pulls an object back toward its center position. (Gravity, Springs, Tension)
Frequency (Hz)
How quickly the back-and-forth motion repeats. Measured in cycles per second .
Amplitude
The size of the motion. CRITICAL: Measure only from the center to the peak, not top to bottom!
The Quake-Catcher
30:00 MISSION
1
THE CHASSIS
Cut slots in the box base. Slide the paper strip through. It must move smoothly!
2
THE PENDULUM
Suspend a weighted cup from the top. Marker tip should "kiss" the paper.
3
THE TEST
Pull the paper at a steady speed while your partner creates a "quake."
Analysis Time
The Calculation Challenge:
Count the peaks in 5 seconds.
Quake Catcher Lab Sheet Quake Catcher Lab
STEM Club: Harmonic Motion & Seismographs
Name:
Date:
Part 1: Defining the Motion
Based on the video, define the following terms in your own words:
Harmonic Motion
Restoring Force
Part 2: The Quake Trace
Attach Your Best Paper Strip Here
Tape your seismograph recording across this area.
Part 3: Data Analysis
Max Amplitude
Measure from the center line to the highest peak.
cm
Wave Count
Total peaks in 5 seconds of pulling.
peaks
Frequency (Hz)
Wave Count ÷ 5 seconds.
Hz
Part 4: Conclusion
1. In your DIY Seismograph, what was the restoring force that pulled the marker back to the center?
2. If you shook the table faster but with smaller movements, what would happen to the Amplitude and Frequency of your trace?
3. Reflection: How is the motion of your marker similar to the "ocean swell" mentioned in the video?
Seismic Swing Answer Key Answer Key & Teacher Notes
Seismic Swing • Quake Catcher Lab
Confidential
Part 1: Defining the Motion
Harmonic Motion
Expected: A back-and-forth motion that repeats over and over again in the same path.
Restoring Force
Expected: The force that always pushes or pulls an object back toward its central/equilibrium position.
Part 3: Data Analysis Calculations
Example Calculation:
Total Peaks (5s)
12
Time Period
5.0s
Calculated Hz
2.4 Hz
(12 ÷ 5 = 2.4)
Part 4: Conclusion Answers
1. The Restoring Force in the Lab:
Gravity. As the cup swings away from the center, gravity pulls it back down toward the lowest point (the center of oscillation).
2. Faster Shaking / Smaller Movements:
The Frequency would increase (more waves per second) and the Amplitude would decrease (shorter distance from the center line).
3. Ocean Swell Connection:
Both are cyclical . The water in a swell moves up and down (harmonic motion) due to gravity, just like our marker moves side-to-side (harmonic motion) due to the tension in the string and gravity.
Quick Diagnostic Checklist
No Trace? The cup is likely too light. Add pennies or washers to the cup to press the marker tip firmly against the paper.Tangled Strings? Ensure all strings are the same length and meet at a single central point at the top of the box.Paper Tearing? The slots in the box are too tight or the paper is being pulled at an angle. 
